Preparation of PEEK Membranes with Excellent Stability Using Common Organic Solvents

Poly(ether ether ketone) (PEEK) is one of the most attractive polymers for organic solvent resistance applications because of its high thermal and organic solvent resistance. However, one of the main disadvantages is that PEEK has to be processed by using harsh solvents, such as methanesulfonic and sulfuric acid. Here, we report for the first time the preparation of PEEK membranes for organic solvent filtration by using common organic solvents. The preparation method consists of the conversion of PEEK into a soluble precursor, followed by dissolution in a mixture of tetrahydrofuran and N,N-dimethylacetamide. The resulting solution is used to obtain the membranes by phase inversion. In the second step, we convert the PEEK precursor to PEEK by treating the obtained membranes with an aqueous acid solution. The resulting PEEK membranes have good permeance and rejection, along with high stability in organic solvents and at high temperatures (up to 140 °C). This procedure opens many possibilities for processing PEEK into membranes by using common techniques to obtain flat sheet membranes or hollow fibers for a broad range of applications.